Substrate cleaning brush preparation sequence, method, and system

ABSTRACT

A method for cleaning top and bottom surfaces of a semiconductor substrate is provided. The method includes scrubbing top and bottom surfaces of the semiconductor wafer with top and bottom brushes, respectively. Top and bottom brushes are saturated and supplied with a scrubbing fluid. The top and bottom brushes are squeezed so as to press out excess scrubbing fluid by continuing to apply top and bottom brushes against top and bottom surfaces of the semiconductor substrate, respectively, but without supplying the scrubbing fluid. Top and bottom brushes are respectively moved away from the top and bottom surfaces of the semiconductor substrate. The top brush is rotated so as to prevent dripping onto the top surface of the semiconductor substrate. Top and bottom surfaces of the semiconductor substrate are rinsed using a rinse fluid while continuing to rotate the top brush that was squeezed to press out the excess scrubbing fluid.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the fabrication ofsemiconductor devices and, more particularly, to cleaning semiconductorsubstrates.

2. Description of the Related Art

As is well known to those skilled in the art, the fabrication ofsemiconductor devices involves numerous processing operations. Theseoperations include, for example, impurity implants, gate oxidegeneration, inter-metal oxide depositions, metallization depositions,photolithography patterning, etching operations, chemical mechanicalpolishing (CMP), etc. Typically, these operations generate contaminantssuch as particles and residue, which are adhered or absorbed by thewafer surfaces. It is well established that contaminants should beremoved from wafer surfaces, as the existence of such contaminants hasdetrimental effects on the performance of the integrated circuitdevices. To achieve this task, wafer surfaces are cleaned as a result ofwhich contaminants such as adhered particles and absorbed compounds(e.g., chemicals) are removed from wafer surfaces.

Normally, double-sided cleaning processing tools are implemented toclean wafer surfaces. FIG. 1 illustrates a cross sectional view of adouble-sided horizontal wafer scrubber 100 designed to clean a topsurface and bottom surface of a wafer 102, in accordance with the priorart. As shown, the wafer scrubber 100 includes a top brush 104 a and abottom brush 104 b, each mounted on a corresponding brush core 106 a andbottom brush core 106 b. Each of the top brush core 106 a and the bottombrush core 106 b includes a top shaft 108 a and a bottom shaft 108 b,each connected to a fluid inlet (not shown in FIG. 1). As shown, theouter surface of top and bottom brushes 104 a and 104 b are covered witha plurality of nodules 104 a and 105 b, respectively.

The wafer 102 is shown to be engaged by a pair of rollers 114 a and 114b. As can be seen, the wafer 102 is held horizontally by the pair ofrollers 114 a and 114 b and top and bottom brushes 104 a and 104 b. Topand bottom surfaces of the wafer 102 are scrubbed, respectively, by topand bottom brushes 104 a and 104 b, which rotate in top and bottom brushrotation directions 110 a and 110 b, correspondingly. The rollers 114 aand 114 b rotate while holding the wafer 102, causing the wafer 102 torotate. The wafer 102 is cleaned as top and bottom brushes 104 a and 104b come in contact with top and bottom surfaces of the wafer 102,removing the contaminants.

Normally, each brush core 108 a and 108 b is connected to a respectivefluid inlet designed to supply fluid into the brush cores 108 a and 108b. Although not shown, each top and bottom brush core 106 a and 106 bhas a plurality of holes thereon allowing fluid to exit top and bottombrush cores 106 a and 106 b so as to flush top and bottom brushes 104 aand 104 b, respectively.

To scrub and rinse wafer top and bottom surfaces thoroughly so as toremove any remaining contaminants, chemicals are initially suppliedthrough the brush (TTB), saturating top and bottom brushes 104 a and 104b. Wafer top and bottom surfaces are then scrubbed by top and bottombrushes 104 a and 104 b for a desired time. Then, top and bottomsurfaces of the wafer 102 are rinsed TTB. That is, top and bottombrushes 104 a and 104 b are flushed and saturated with DI water so as toeliminate scrubbing chemicals in top and bottom brushes 104 a and 104 bas well as disposing of any contaminant remaining on top and bottomsurfaces of the wafer 102. The rinse operation thereafter continuesuntil any and all contaminants remaining on top and bottom surfaces ofthe wafer have been removed. At this point, the cleaned wafer is removedfrom the brush scrubber 100, allowing the next wafer to be placed on therollers 114 a and 114 b. In this fashion, each wafer is scrubbed andrinsed in the prior art brush scrubber 100.

Repeatedly flushing top and bottom brushes 104 a and 104 b withchemicals followed by rinsing of the chemicals out of top and bottombrushes 104 a and 104 b using de-ionized water is not without negativeconsequences. For instance, a significant amount of chemicals is wastedduring each and every brush scrubbing operation. The brushes arcsaturated with chemicals to perform the scrubbing operation. Immediatelythereafter the brushes are rinsed with DI water, ultimately resulting inwasting a substantial amount of chemicals, overall. In addition towasting chemicals, the pH of top and bottom brushes 104 a and 104 b isrepeatedly and constantly oscillating, undesirably creating a constantnon-equilibrium in top and bottom brushes 104 a and 104 b.

Another negative effect of TTB scrubbing and rinse operation isreintroduction of contaminants onto the wafer top and bottom surfaces.For instance, residues remaining in top and bottom brushes arere-introduced into the rinsing interface by the rinse fluid applied TTB.Additionally, chemicals in top brush drip on to the top surface of thewafer, recontaminating the wafer top surface having the activecomponents, damaging the wafers and significantly reduce waferthroughput.

In view of the foregoing, there is a need for an improved semiconductorprocessing apparatus and methodology capable of minimizing wasting ofchemicals during cleaning operation while increasing wafer throughputthrough preventing recontamination of wafer surfaces.

SUMMARY OF THE INVENTION

Broadly speaking, the present invention fills these needs by providingan apparatus and methodology capable of substantially minimizing fluidsused during substrate cleaning operations while increasing waferthroughput. In one embodiment, top and bottom surfaces of the wafers arecleaned in a brush scrubber-rinse module. In one embodiment, top andbottom brushes of the brush scrubber-rinse module saturated withscrubbing fluid are implemented to scrub wafer top and bottom surfacesthrough the brush (TTB). Top and bottom brushes are squeezed,eliminating excess scrubbing fluid. Top and bottom surfaces of the waferare then rinsed using a rinse fluid introduced onto the wafer top andbottom surfaces through respective rinse nozzles.

It should be appreciated that the present invention can be implementedin numerous ways, including as a process, an apparatus, a system, adevice, or a method. Several inventive embodiments of the presentinvention are described below.

In one embodiment, a method for cleaning top and bottom surfaces of asemiconductor substrate is provided. The method includes scrubbing a topsurface of the semiconductor wafer with a top brush and a bottom surfaceof the semiconductor substrate with a bottom brush. The top brush andthe bottom brush are saturated and supplied with a scrubbing fluid. Themethod also includes squeezing the top brush and the bottom brush so asto press out excess scrubbing fluid by continuing to apply the top brushagainst the top surface and the bottom brush against the bottom surfaceof the semiconductor substrate, but without supplying the scrubbingfluid. The method further includes moving the top brush away from thetop surface of the semiconductor substrate and the bottom brush from thebottom surface of the semiconductor substrate. Also included is rotatingthe top brush to prevent dripping onto the top surface of thesemiconductor substrate. The method also includes rinsing the top andbottom surfaces of the semiconductor substrate using a rinse fluid whilecontinuing to rotate the top brush that was squeezed to press out theexcess scrubbing fluid.

In another embodiment, a method for cleaning a semiconductor substrateis provided. The method includes scrubbing a top surface of thesemiconductor substrate with a top brush and a bottom surface of thesemiconductor substrate with a bottom brush. The top brush and thebottom brush are saturated with a scrubbing fluid. Also included issqueezing the top brush and the bottom brush so as to press out excessscrubbing fluid. The method further includes moving the top brush awayfrom the top surface of the semiconductor substrate and the bottom brushfrom the bottom surface of the semiconductor substrate while rotatingthe top brush. Further included in the method is rinsing top and bottomsurfaces of the semiconductor substrate using a rinse fluid.

In yet another embodiment, a method for cleaning top and bottom surfacesof a semiconductor substrate is provided. The method includes scrubbinga top surface of the semiconductor substrate with a top brush and abottom surface of the semiconductor substrate with a bottom brush. Thetop brush and the bottom brush are saturated and supplied with ascrubbing fluid. The method also includes squeezing the top brush andthe bottom brush so as to press out excess scrubbing fluid by continuingto apply the top brush against the top surface and the bottom brushagainst the bottom surface of the semiconductor substrate, but withoutsupplying the scrubbing fluid. Also included in the method is moving thetop brush to a side of the top surface of the semiconductor substrateand moving the bottom brush away from the bottom surface of thesemiconductor substrate to prevent dripping onto the top surface of thesemiconductor substrate. Also included is rinsing the top and bottomsurfaces of the semiconductor substrate using a rinse fluid.

In still a further embodiment, a method for cleaning top and bottomsurfaces of a semiconductor substrate is provided. The method includesscrubbing a top surface of the semiconductor wafer with a top brush anda bottom surface of the semiconductor substrate with a bottom brush. Thetop brush and the bottom brush are saturated with a scrubbing fluid. Themethod also includes squeezing the top brush and the bottom brush so asto press out excess scrubbing fluid. Also included is moving the topbrush away from the top surface of the semiconductor substrate and thebottom brush from the bottom surface of the semiconductor substratewhile rotating the top brush. Further included in the method is rinsingthe top and bottom surfaces of the semiconductor substrate using a rinsefluid.

The advantages of the present invention are numerous. Most notably, incontrast to the double-sided wafer scrubbers of the prior art in whichcleaning fluid and rinsing fluid are introduced into the cleaninginterface through the brush (TTB), the embodiment of the presentinvention introduce scrubbing fluid to the cleaning interface TTB duringthe scrubbing operation. However, top and bottom surfaces of the waferare rinsed using rinse fluid delivered onto the wafer surfaces usingrinse nozzles. In this manner, there is substantially no need to flushout the scrubbing fluid in the brushes before performing the rinseoperation. Another advantage of the embodiments of the present inventionis that the concentration of scrubbing chemicals in the brushes areremained substantially constant. Still another advantage of the presentinvention is that the overall use of chemicals during the cleaningoperation is substantially reduced. Yet another advantage of theembodiments of the present invention is that the scrubbing and rinseoperations are performed in a single module. Still another advantage isthat the embodiments of the present invention substantially eliminatethe possibility of recontamination of the wafer surfaces throughdripping of scrubbing liquid. Yet another advantage is that theembodiments of the present invention substantially prevent introductionof contaminants remaining in the brushes onto the wafer surfaces.

Other aspects and advantages of the invention will become apparent fromthe following detailed description, taken in conjunction with theaccompanying drawings, illustrating by way of example the principles ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be readily understood by the followingdetailed description in conjunction with the accompanying drawings, andlike reference numerals designate like structural elements.

FIG. 1 is a simplified cross-sectional view of a prior art horizontalwafer scrubber.

FIG. 2A is a simplified three-dimensional view of an exemplarydouble-sided brush scrubber-rinse module, in accordance with oneembodiment of the present invention.

FIG. 2B is a simplified top view depicting scrubbing of a top surface ofa wafer in an exemplary horizontal double-sided brush scrubber-rinsemodule, in accordance with one embodiment of the present invention.

FIG. 2C is a simplified top view depicting rinsing of a top surface of awafer in an exemplary horizontal double-sided brush scrubber-rinsemodule, in accordance with still another embodiment of the presentinvention.

FIG. 3A is a simplified, exploded, cross sectional view depictingscrubbing of top and bottom surfaces of the wafer in an exemplarydouble-sided scrubber-rinse module, in accordance with still anotherembodiment of the present invention.

FIG. 3B is a simplified, exploded, cross sectional view depictingrinsing of top and bottom surfaces of the wafer in an exemplarydouble-sided scrubber-rinse module, in accordance with still anotherembodiment of the present invention.

FIG. 3C is a simplified cross sectional view depicting different stagesof an exemplary scrubbing-rinse operation as performed in an exemplaryscrubber-rinse module, in accordance with still another embodiment ofthe present invention.

FIG. 4A is a partial, simplified, exploded, cross sectional view of atop brush of an exemplary scrubber-rinse module, in accordance withstill another embodiment of the present invention.

FIG. 4B is a partial, simplified, exploded, cross sectional view of thetop brush shown in FIG. 4A being applied to a wafer top surface, inaccordance with still another embodiment of the present invention.

FIG. 5A is a simplified top view of the top surface of an exemplarywafer being rinsed by a rinse fluid 218, in accordance with stillanother embodiment of the present invention.

FIG. 5B is a partial, simplified, cross sectional view of the wafershown in FIG, 5A being rinsed, in accordance with still anotherembodiment of the present invention.

FIG. 6A is a plot illustrating changes in the amount of scrubbing fluidin, top and bottom brushes during an exemplary scrubbing-rinseoperation, in accordance with still another embodiment of the presentinvention.

FIG. 6B is a plot illustrating the consistent concentration of scrubbingfluid in top and bottom brushes during an exemplary scrubbing-rinseoperation, in accordance with still another embodiment of the presentinvention.

FIG. 7A is a simplified, exploded, cross sectional view depictingscrubbing of top and bottom surfaces of the wafer in an exemplarydouble-sided scrubber-rinse module, in accordance with still anotherembodiment of the present invention.

FIG. 7B is a simplified, exploded, cross sectional view depictingrinsing of top and bottom surfaces of the wafer in an exemplarydouble-sided scrubber-rinse module, in accordance with still anotherembodiment of the present invention.

FIG. 8A is a flow chart diagram illustrating the method operationsperformed in an exemplary scrubber-rinse module, in accordance withanother embodiment of the present invention.

FIG. 8B is a flow chart diagram illustrating the method operationsimplemented during the scrubbing operation of FIG. 8A, in accordancewith another embodiment of the present invention.

FIG. 8C is a flow chart diagram illustrating the method operationsimplemented during the squeezing operation of FIG. 8A, in accordancewith another embodiment of the present invention.

FIG. 8D is a flow chart diagram illustrating the method operationsimplemented during the rinse operation of FIG. 8A, in accordance withanother embodiment of the present invention.

FIG. 9 is a flowchart diagram illustrating method operations performedin another exemplary scrubber-rinse module, in accordance with yetanother embodiment of the present invention.

FIG. 10 is a flowchart diagram illustrating method operations performedin another exemplary scrubber-rinse module, in accordance with stillanother embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An invention capable of substantially minimizing fluids implementedduring a cleaning operation while increasing wafer throughput bypreventing recontamination of wafer surfaces is provided. In oneembodiment, a brush scrubber-rinse module for cleaning wafer top andbottom surfaces is provided. In one preferred embodiment, top and bottombrushes of the brush scrubber-rinse module are saturated with scrubbingfluid. Top and bottom brushes are implemented to scrub wafer top andbottom surfaces using scrubbing fluid introduced into a scrubbinginterface through the brush (TTB). Supplying of scrubbing fluid isceased while top and bottom brushes are still being applied to wafer topand bottom surfaces, squeezing excess scrubbing fluid out of top andbottom brushes. In one exemplary embodiment, top and bottom brushes aremoved away from wafer top and bottom surfaces. In another example, topand bottom brushes arc configured to continue rotating until excessscrubbing fluid is pressed out of top and bottom brushes. In yet anotherexample, the top brush is configured to continue rotating until excessscrubbing fluid has been eliminated from the top brush while the bottombrush is remained stationary, preventing recontamination of wafer topsurface. In still another embodiment, the top brush is moved to a sideof the wafer top surface such that any dripping of scrubbing fluid ontowafer top surface is prevented.

Wafer top and bottom surfaces are then rinsed using rinse fluid directedonto approximately centers of wafer top and bottom surfaces through topand bottom nozzles. Preferably, rinse fluid is applied onto wafer topand bottom surfaces such that a rinse fluid main stream is substantiallydirected at respective centers of wafer top and bottom surfaces. In thismanner, the rinse fluid is prevented from diluting the concentration ofthe scrubbing fluid in top and bottom brushes.

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the present invention. Itwill be understood, however, to one skilled in the art, that the presentinvention may be practiced without some or all of these specificdetails. In other instances, well known process operations have not beendescribed in detail in order not to unnecessarily obscure the presentinvention. FIG. 1 was discussed above in the “Background of theInvention” section. It should be appreciated that the term “about” asused herein, refers to a range of +/−10%.

FIG. 2A is a simplified three-dimensional view of an exemplarydouble-sided wafer brush scrubber-rinse module 200, in accordance withone embodiment of the present invention. As shown, the waferscrubber-rinse module 200 includes a top brush 204 a and a bottom brush204 b, each of which is mounted on a corresponding brush core 206 a andbottom brush core 206 b. Each of the top brush core 206 a and the bottombrush core 206 b includes a top shaft 208 a and a bottom shaft 208 b,each connected to a top fluid inlet 209 a and a bottom fluid inlet 209b. As shown, the outer surface of top and bottom brushes 204 a and 204 bare covered with a plurality of nodules 204 a and 205 b, respectively.Top and bottom surfaces of the wafer 102 are configured to be scrubbedby: the corresponding top and bottom brushes 204 a and 204 b andsubsequently rinsed using respective top and bottom rinse nozzles 216 aand 216 b.

The wafer 102 is shown to be engaged by two engaging rollers 214 a and214 b and a driving roller 214 c. As can be seen, during the scrubbingoperation, the wafer 102 is held horizontally by the engaging rollers214 a and 214 b and the driving roller 214 b and top and bottom brushes204 a and 204 b. The wafer 102 is rotated in a wafer rotation direction112 by the driving roller 214 c. Additional information regarding themechanism of the driving roller 214 c and the engaging rollers 214 aduring the scrubbing and rinse operations is provided below with respectto FIGS. 2B-2C. As can be seen, top and bottom brushes 204 a and 204 bare configured to rotate around an axis of rotation in respectiverotation directions 110 a and 110 b. In this manner, top and bottomsurfaces of the wafer 102 are cleaned as top and bottom brushes 204 aand 204 b come into contact with top and bottom surfaces of the wafer102.

In one embodiment, top and bottom brushes 204 a and 204 b are polyvinylalcohol (PVA) brushes (i.e., a very soft sponge), which can dislodgecontaminants such as particles and residues using the scrubbing fluid207. In must be noted, however, that in another example, top and bottombrushes 204 a and 204 b can be constructed from any suitable material solong as the material can dislodge particles and residues remaining ontop and bottom surfaces of the wafer.

With continued reference to FIG. 2A, the wafer 102 is shown to rotate inthe wafer rotation direction 112 while top and bottom brushes 204 a and204 b rotate in the corresponding rotation direction 110 a and 110 b andapply equal but opposite forces to the wafer top and bottom surfaces.

Top and bottom brush cores 206 a and 206 b arc shown to be connected torespective top and bottom fluid inlets 209 a and 209 b designed tosupply scrubbing fluid into the brush cores 208 a and 208 b. Each topand bottom brush core 206 a and 206 b has a plurality of holes thereon(not shown in this FIG,) allowing the scrubbing fluid 207 to exit topand bottom brush cores 206 a and 206 b, saturating top and bottombrushes 204 a and 204 b, respectively. In this manner, scrubbing fluid207 is introduced into the scrubbing interface, allowing top and bottomsurfaces of the wafer be scrubbed and cleaned. In one embodiment, topand bottom surfaces of the wafer 102 are scrubbed using de-ionized wateror any aqueous or semi-aqueous chemical solution. It must be appreciatedby one having ordinary skill in the art that the scrubbing fluid 207 canbe any suitable fluid capable of cleaning top and bottom surfaces of thewafer (e.g., Standard Cleaning I (SCI), DI water, ammonia containingchemical mixtures, HF containing chemical mixtures, surfactantcontaining chemical mixtures, etc.) In one implementation, the scrubbingfluid may be a cleaning fluid as described in U.S. Pat. No. 6,405,399,issued on Jun. 18, 2002, having inventors Jeffrey J. Farber and Julia S.Svirchevski, and entitled “Method and System of Cleaning a Wafer AfterChemical Mechanical Polishing or Plasma Processing.” This U.S. Patent,which is assigned to Lam Research Corporation, the assignee of thesubject application, is incorporated herein by reference.

As can be seen, the wafer scrubber-rinse module 200 of the presentinvention further includes top and bottom rinse nozzles 216 a and 216 b.Top and bottom rinse nozzles 216 a and 216 b arc defined within themodule such that rinse steam 218′ is, substantially directed to therespective centers of top and bottom surfaces of the wafer 102.Additional information regarding the rinse operation using top andbottom rinse nozzles 216 a and 216 b are provided below.

Reference is made to the simplified top view diagrams depicted in FIGS.2B and 2C, respectively, showing scrubbing and rinsing of an exemplarytop surface of the wafer 102 in a double-sided brush scrubber-rinsemodule 200, in accordance with one embodiment of the present invention.As can be seen in FIG. 2B, the wafer 102 is engaged by the engagingrollers 214 a and 214 b and the driving roller 214 c. In one embodiment,the driving roller 214 c is configured to cause the wafer 102 to rotatein the rotation direction 112 while the driving roller still engages thewafer 102. In another embodiment, rollers 214 a, 214 b, and 214 c can beconfigured to be implemented to cause the wafer 102 to rotate in therotation direction 112.

As further shown, during the scrubbing operation, top and bottom brushes204 a and 204 b are brought into contact with the wafer 102 as the topand bottom brushes 204 a and 204 b are being flushed with scrubbingfluid 207 through top and bottom fluid inlets 208 a and 208 b,respectively. Thus, during the scrubbing operation, the wafer 102 isalso being held horizontally by top and bottom brushes 204 a and 204 b.As can be seen in FIG. 2B, the top nozzle 216 a is defined within themodule such that rinse fluid is directed substantially toward the centerof the wafer top surface. However, as can be seen, no rinse fluid isbeing supplied during the scrubbing operation.

FIG. 2C, comparatively, shows the top surface of the wafer 102 beingrinsed by rinse fluid 218 being introduced through the top nozzle 216 a.As can be seen, the supplying of the scrubbing fluid 207 has seized andthe rinse fluid spray stream 218′ is directed toward the center of thewafer top surface. In this matter, the centrifugal force generated bythe rotation of the wafer 102 causes the rinse fluid 218 to be spreadover the top wafer surface, cleaning the top wafer surface. As will bediscussed in more detail with respect to FIG. 3B, the top brush 204 ashown in the embodiment of FIG. 2C no longer is in contact with thewafer top surface.

FIGS. 3A and 3B are simplified cross sectional views of an exemplarydouble-sided scrubber-rinse module, in accordance with one embodiment ofthe present invention. As shown in FIG. 3A, top and bottom brushes 204 aand 204 b come into contact with top and bottom surfaces of the wafer102, as top and bottom brushes 204 a and 204 b are respectively rotatingin top and bottom rotation directions 110 a and 110 b. As can been seen,the wafer 102 is held horizontally by the engaging wafers 214 a and 214b and driving roller 214 c (not shown in this figure) while top andbottom brushes 204 a and 204 hold the wafer 102. Top and bottom brushes204 a and 204 b respectively apply equal but opposite pressure to topand bottom surfaces of the wafer 102, as can be seen by the suppressionof top and bottom brushes 204 a and 204 b.

During the scrubbing operation, top and bottom brushes 204 a and 204 bare flushed with scrubbing fluid 207, saturating top and bottom brushes204 a and 204 b with scrubbing fluid 207. As can be seen, no rinse fluidis being supplied during the scrub operation. In one embodiment, top andbottom brushes 204 a and 204 b are configured to rotate betweenapproximately about 100 and 400 RPMs, and a more preferred range ofapproximately about 200 and 400 RPMs and most preferably approximatelyabout 200-250 RPMs during the rinse operation.

In one example, once the wafer 102 has been scrubbed for a desiredamount of time, supplying of the scrubbing fluid is stopped. Theapplication of the rotating top and bottom brushes 204 a and 204 b totop and bottom surfaces of the wafer 102, however, still continues. Inthis manner, any excess scrubbing fluid 207 saturating top and bottombrushes 204 a and 204 b is squeezed out of top and bottom brushes 204 aand 204 b. As can be seen, top and bottom brushes 204 a and 204 b arestill rotating in, rotation directions 110 a and 110 b, respectively,during the squeezing operation. The squeezing operation advantageouslyprevents dripping of scrubbing fluid 207, which naturally occurs whentop and bottom brushes 204 a and 204 b are saturated with fluid.

The embodiment shown in FIG. 3B depicts top and bottom surfaces of thewafer 102 being rinsed using the rinse fluid 218 introduced through therespective top and bottom nozzles 216 a and 216 b. As can be seen, topand bottom brushes 204 a and 204 b are no longer saturated with thescrubbing fluid 207 a and 207 b, respectively. In one example, after thescrubbing operation has concluded, the scrubbing of top and bottomsurfaces of the wafer by top and bottom brushes 204 a and 204 b iscontinued until a percentage of the scrubbing fluid is pressed out oftop and bottom brushes 204 a and 204 b.

As can be seen in FIG. 3B, while the wafer 102 is still engaged by theengaging rollers 214 a and 214 b and the driving roller 214 c, the wafer102 is no longer in contact with top and bottom brushes 204 a and 204 b.Top and bottom brushes 204 a and 204 b are shown to have been moved awayfrom the respective top and bottom surfaces of the wafer 102.

Specifically, the top brush 204 a has been moved above the top surfaceof the wafer 102 such that a distance 215 a has been created between thelowermost portion of the top brush 204 a and the wafer top surface. In alike manner, the bottom brush 204 b is moved below the bottom surface ofthe wafer 102 for a distance of 215 b. As shown, the topmost portion ofthe bottom brush 204 b is shown to have a distance 215 b from the waferbottom surface.

In the embodiment shown in FIG. 3B, top and bottom brushes 204 a and 204b are shown to be rotating in rotation directions 110 a′ and 110 b′. Inone embodiment, the top brush 204 a may continue rotating so as toprevent the scrubbing fluid remaining in the top brush 204 a from beingreintroduced into the rinse interface. Thus, in one preferredembodiment, the scrubbing fluid in the bottom brush 204 b may be allowedto drip, because any scrubbing fluid droplets cannot be dripped onto thewafer bottom surface.

By way of example, top and bottom brushes 204 a and 204 b can beconfigured to rotate between approximately about 2 and 60 RPMs, and amore preferred range of approximately about 10 and 60 RPMs and mostpreferably approximately about 20 RPMs during the rinse operation.

Subsequent to moving top and bottom brushes 204 a and 204 b above andbelow top and bottom surfaces of the wafer, rinsing top and bottomsurfaces of the wafer 102 is initiated. As can be seen, rinse fluid 218is shown to be introduced onto the wafer top and bottom surfaces usingtop and bottom rinse nozzles 216 a and 216 b. Rinse fluid spray stream218′ is shown to be directed onto respective centers of top and bottomsurfaces of the wafer 102. However, the rinse fluid spray stream 218′ isshown to be applied onto the wafer top and bottom surfaces withoutcontacting top and bottom brushes 204 a and 204 b. This is possible dueto the distances 215 a and 215 b defined between top and bottom brushes204 a and 204 b and top and bottom surfaces of the wafer 102,respectively. As can be appreciated, defining top and bottom rinsenozzles 216 a and 216 b such that a rinse fluid main stream cannot comeinto contact with top and bottom brushes 204 a and 2104 b is beneficialas the concentration of the scrubbing fluid 207 in top and bottombrushes 204 a and 204 b remains substantially consistent. Theconcentration remains substantially the same as there does not exist thenecessity to rinse out top and bottom brushes 204 a and 204 b prior tothe rinse operation.

In one embodiment, each of the distances 215 a and 215 b areapproximately about ⅜ inch. In another example, each of the distances215 a and 215 b can be approximately about .2 inches or greater so longas the rinse fluid main stream cannot substantially contact top andbottom brushes 204 a and 204 b. It must be noted by one of ordinaryskill in the art, however, that the distances 215 a and 215 b aredependent on hardware limitations. As such, in another embodiment, thedistances 214 a and 215 b can be defined to be any suitable distance solong as the rinse fluid main stream is prevented from being applied ontotop and bottom brushes 204 a and 204 b.

In accordance with one embodiment, internal diameters of top and bottomrinse nozzles 216 a and 216 b can be between approximately about{fraction (1/16)} inch and ⅜ inch, and a more preferred range ofapproximately about ⅛ and {fraction (1/4)} inch, and most preferablyapproximately about ⅛ inch.

Furthermore, in one implementation, the flow rate of the rinse fluid 207can be between approximately about 0.5 and 2 liters/minute, and a morepreferred range of approximately about 0.7 and 1.5 liter/minutes, andmost preferably approximately about 1 liter/minute during the rinseoperation. In another embodiment, the flow rate of scrubbing fluid 207can be between approximately about 0.3 and 1.5 liters/minute, and a morepreferred range of approximately about 0.5 and 1.0 liter/minutes, andmost preferably approximately about 0.7 liter/minute during thescrubbing operation.

In one example, the wafer 102 can be configured to rotate betweenapproximately about 100 RPMs and 400 RPMs, and a more preferred range ofapproximately about 200 and 300 RPMs and most preferably approximatelyabout 250 RPMs during the rinse operation.

Reference is made to FIG. 3C depicting different stages of an exemplaryscrubbing-rinse operation, as performed in an exemplary scrubber-rinsemodule, in accordance with one embodiment of the present invention. Asshown, at time t0, top and bottom brushes 204 a and 204 b arerespectively shown to be contacting top and bottom surfaces of the wafer102. At this point, the scrubbing operation has not yet been initiated.Proceeding to time t1, top and bottom brushes 204 a and 204 b saturatedwith the scrubbing fluids 207 a and 207 b are shown to be scrubbing topand bottom surfaces of the wafer 102, correspondingly. As can be seen,scrubbing fluids 207 a and 207 b are fed to top and bottom brushes,respectively, through the corresponding inlets 209 a and 209 b.

At time t2, supplying of scrubbing fluids 207 a and 207 b is shown tohave ceased and the squeezing operation has been initiated. As shown,while rotating in the rotation direction 110 a and 110 b, respectively,top and bottom brushes 204 a and 204 b are applied to top and bottomsurfaces of the wafer 102. In this manner, excess scrubbing fluids 207 aand 207 b are squeezed out of top and bottom brushes 204 a and 204 b.

At time t3, top and bottom brushes 204 a and 204 b are shown to havebeen moved away from corresponding wafer top and bottom surfaces suchthat top and bottom brushes 204 a and 204 b are no longer in contactwith top and bottom surfaces of the wafer 102. The top brush 204 a hasbeen moved above the top surface of the wafer 102 such that a distance215 a has been created between the lowermost portion of the top brush204 a and the wafer top surface. In a like manner, the bottom brush 204b is moved below the bottom surface of the wafer 102 for a distance 215b. As shown, the topmost portion of the bottom brush 204 b is shown tohave a distance 215 b from the wafer bottom surface.

As can be appreciated, the top brush 204 a is rotating in rotationdirection 110 a′. In this manner, any scrubbing fluid 207 a collected atthe lowermost portion of the top brush 204 a is prevented from beingdripped onto the top surface of the wafer 102. As can be seen, whileboth top and bottom brushes 204 a and 204 b are moved away for therespective distance of 215 a and 215 b, in this embodiment, the topbrush 204 a is shown to be rotating. As can be appreciated, in oneexample, any scrubbing fluid 207 collected at the lowermost portion ofthe bottom brush 204 b may not be dripped onto the wafer bottom surface.As such, in this example, the bottom brush can be configured to remainstationary during rinse operation.

Continuing to time t4, the rinse fluid 218 is shown to have beenintroduced onto wafer top and bottom surfaces using respective top andbottom rinse nozzles 216 a and 216 b. The rinse fluid spray stream 218′is shown to be directed onto the respective centers of wafer top andbottom surfaces such that the rinse fluid main stream 217 cannot besprayed onto top and bottom brushes 204 a and 204 b. Thus, by definingtop and bottom rinse nozzles 216 a and 216 b such that the rinse fluidmain stream is prevented from coming into contact with top and bottombrushes 204 a and 204 b, the concentration of the scrubbing fluids 207 aand 207 b can remain substantially consistent. This ensues as there doesnot exist a need to flush out the scrubbing fluid out of top and bottombrushes 204 a and 204 b prior to performing the rinse operation.Furthermore, the rinse fluid 218 cannot come into contact with top andbottom brushes 204 a and 204 b so as to lower the concentration of thescrubbing fluids 207 a and 207 b.

In one exemplary embodiment, the brush squeeze operation can beperformed between approximately about 3 and 20 seconds, and a morepreferred range of approximately about 3 and 15 seconds and mostpreferably approximately about 7 seconds. In this manner, a brushscrubbing operation can be performed between approximately about 20 and120 seconds, and a more preferred range of approximately about 20 and 40seconds and most preferably approximately about 30 seconds.

Compressibility of an exemplary top brush 204 a is shown in FIGS. 4A and4B, in accordance with one embodiment of the present invention. As canbe seen, the top brush 204 shown in the embodiment of FIG. 4A is not incontact with the wafer top surface. As such, the top brush 204 a is notapplying any pressure onto the wafer top surface. At this point, thecompression of the top brush 204 a is approximately about 0.

Comparatively, the top brush 204 a of FIG. 4B is being applied onto thewafer top surface 102 with pressure, causing the top brush 204 a to becompressed. That is, when the top brush 204 a is brought into contactwith the wafer top surface, the top brush 204 a is compressed by certainnumber of millimeters. As shown in FIG. 4B, a total brush movement ofthe top brush 204 a being applied onto the wafer top surface isapproximately about distance 222 a. In one example, the Tespective totalbrush movements of top and bottom brushes 204 a and 204 b are configuredto range from approximately about 0 percent to approximately about 30percent of the thickness of the corresponding top and bottom brushes 204a and 204 b.

In one exemplary embodiment, each of the top and bottom brushes 204 aand 204 b can be configured to compress between approximately about 0and 12 millimeters, and a more preferred range of approximately about 2and 8 millimeters and most preferably approximately about 6 millimeterswhen respectively applied onto wafer top and bottom surfaces.

As can be appreciated, top and bottom brushes 204 a and 204 b of FIGS.4A and 4B are flat brushes, as top and bottom brushes 204 a and 204 bdoes not include any nodules. Thus, although the embodiments of thepresent invention are shown to have implemented top and bottom brushes204 a and 204 b having substantially the same characteristics (e.g.,length, diameter, compression, etc.), in a different embodiment of thepresent invention, top and bottom brushes 204 a and 204 b may havedifferent characteristics (e.g., be nonsymmetrical) so long as thebrushes can scrub substantially the entire wafer top and bottomsurfaces. In one implementation, the brush scrubber-rinse module is anasymmetric brush scrubbing system as described in U.S. application Ser.No. 10/017,109, filed on Dec. 13, 2001, having inventors Michael Ravkin,John de Larios, and Katrina Mikhaylich, and entitled “Method andApparatus for Asymmetric Processing of Front side and Back side ofSemiconductor Substrates.” This U.S. Application, which is assigned toLam Research Corporation, the assignee of the subject application, isincorporated herein by reference.

It must be noted that different top and bottom scrub fluids may beimplemented to respectively scrub wafer top and bottom surfaces so longas top and bottom scrubbing fluids cannot interact with each other. Insome embodiments, when wafer top and bottom surfaces are scrubbed withdifferent scrubbing fluids, interaction between the fluids should beavoided. In a like manner, different top and bottom rinse fluids can beimplemented to rinse wafer top and bottom surfaces. Similar to thescrubbing fluids, in some embodiments in which wafer top and bottomsurfaces are rinsed with different rinse fluids, interaction between thefluids should be avoided.

FIG. 5A is a simplified top view of the top surface of an exemplarywafer 102 being rinsed by rinse fluid 218, in accordance with oneembodiment of the present invention. FIG. 5B is a simplified, exploded,cross sectional view of the wafer 102 being rinsed, depicting the rinsefluid main stream 217 of the rinse fluid spray stream 218′,in accordancewith one embodiment of the present invention. As can be seen, the rinsefluid main stream 217 is directed onto a wafer center 102 c through thetop rinse nozzle 216 a. In a preferred embodiment, as the wafer 102rotates in the wafer rotation direction 112, the rinse fluid 218 isspread substantially evenly onto the wafer top surface in a direction224. This occurs as a result of the centrifugal force created by therotation of the wafer 102. In this manner, wafer top and bottom surfacesare substantially rinsed, beneficially eliminating any remainingcontaminants thereon without having to introduce rinse fluid through topand bottom brushes 204 a and 204 b, substantially reducing overall wastein cleaning and rinse chemicals.

FIG. 6A is a plot illustrating a graph 234 of changes in the amount ofscrubbing fluid in top and bottom brushes during an exemplaryscrubbing-rinse operation, in accordance with one embodiment of thepresent invention. As shown, the amount of scrubbing fluid in anexemplary brush at time to is shown to be at a point 228 of the graph234. Wafer 1 is shown to be scrubbed between the time t0 and t1 duringwhich the amount of scrubbing fluid in the brushes is remainedsubstantially constant, creating a substantially flat portion A of thegraph 234. The substantially flat portion A also corresponds to thesupplying of scrubbing fluid to the brushes and the scrubbing interfaceat a constant flow rate during the scrubbing operation.

Portion B of the graph 234 is shown to have taken a steep drop betweentimes t1 and t2. This steep plunge corresponds to the squeezingoperation performed during the times t1 and t2 during which supplying ofscrubbing fluid to the brushes is ceased further accompanied byeliminating excess scrubbing fluid from the brushes. The portion C ofthe graph 234 (i.e., portion of the graph defined between points 234 band 234 c of the graph 234), corresponds to the rinse operation, asperformed between times t2 and t3. As shown, the portion C of the graphis substantially flat, revealing that the amount of the scrubbing fluidin the brushes remains substantially constant during the rinseoperation. As discussed in more detail above, the amount of scrubbingfluid remains substantially unchanged as in one exemplary embodiment,the brushes rotate during the rinse operation, preventing any scrubbingfluid from dripping onto top and bottom surfaces of the wafer.Additionally, by directing the rinse fluid onto the wafer surfaces suchthat the rinse fluid main stream is directed substantially to the centerof the wafer, the embodiments of the present invention prevent rinsefluid from contacting the brushes. As such, the amount of scrubbingfluid in the brushes remains substantially constant. At this point,scrubbing-rinsing of wafer 1 has concluded.

As can be seen, a portion D of the graph 234 corresponding to time t3and t4 depicts supplying of the scrubbing fluid to the brushes to scrubthe next wafer, wafer 2. As can be seen in portion D, graph 234 makes asubstantially sharp climb between times t3 and t4. This sharp rise isdue to supplying of fluid into the brushes for scrubbing wafer. 2.Thereafter, a portion E of the graph 234 is shown to be substantiallyconstant between time t4-t5, correlating to the scrubbing operation,during which the amount of fluid in the brushes remains substantiallyconstant. As further shown, a portion F of the graph 234 makes anothersharp decline between time t5 and t6, correlating with the squeezingoperation performed after scrubbing the wafer 2.

In comparison, FIG. 6B depicts a plot of concentration versus time ofscrubbing fluid in an exemplary brush in an exemplary scrubber-rinsemodule, in accordance with one embodiment. As shown, a graph 226 is asubstantially flat graph revealing the capability of the embodiments ofthe present invention to maintain the concentration of the scrubbingfluid constant during the scrubbing and rinse operations.

Reference is made to FIGS. 7A and 7B illustrating yet another brushscrubber-rinse module, in accordance with another embodiment of thepresent invention. In the brush scrubber-rinse module of FIG. 7A, thewafer 102 is shown to be engaged by the two engaging rollers 214 a and214 b and the driving roller 214 c (not shown in this figure). Top andbottom brushes 304 a and 304 b saturated with the scrubbing fluid 207are rotating in the respective rotation direction 110 a and 110 b,scrubbing top and bottom surfaces of the wafer 102. Then, as describedin more detail above with respect to FIGS. 3A-3C, supplying of thescrubbing fluid 207 is stopped. However, top and bottom brushes 304 aand 304 b are applied onto top and bottom surfaces of the wafer so a toeliminate excess scrubbing liquid 207.

In the embodiment of FIG. 7B, the top brush 304 a is shown to have beenmoved to the side of the wafer 102 such that the wafer 102 cannot berecontaminated by droplets 207′ of the scrubbing liquid 207. As can beseen in the embodiment of FIG. 7B, the top brush 304 a is moved to theside of both, the wafer 102 as well as the engaging roller 214 b. Inthis manner, droplets 207′ cannot be reintroduced onto the wafer topsurface through the engaging roller 214 b.

Although the top brush 304 a is shown to have been moved to the side ofthe wafer, the bottom brush 304 b is shown to have been lowered by thedistance 215 b. In one exemplary embodiment, during the rinse operation,the top brush 304 a having been moved to the side of and the bottombrushes 304 b are configured to remain stationary as substantially noneof the droplets 207′ of the scrubbing fluid 207 can come into contactwith the wafer top and bottom surfaces, re-contaminating the wafersurfaces. As can be appreciated, one of ordinary skill in the art shouldappreciate that in another implementation, either the top brush 304 a orthe bottom brush 304 b or both can be configured to rotate during therinse operation. Furthermore, as can be seen, the top brush 304 a isshown to have further moved up the distance 215 a. However, in anotherembodiment, the top brush 304 a may not require to be moved away fromthe wafer top surface.

Although symmetrical pressure is shown to be applied by top and bottombrushes 204 a and 204 b and 304 a and 304 b, it must be noted that theembodiments of the present can be implemented such that nonsymmetricalpressure is applied to top and bottom surfaces of the wafer by top andbottom brushes, respectively. Of course, it must be appreciated by onehaving ordinary skill in the art that nonsymmetrical pressure can beapplied so long as application of nonsymmetrical pressure does notresult in breaking of the wafer.

Reference is made to a flowchart 800 of FIG. 8A depicting methodoperations performed in an exemplary scrubber-rinse module, inaccordance with one embodiment of the present invention. The methodbegins in operation 802 in which top and bottom surfaces of the waferare scrubbed using top and bottom brushes. Top and bottom brushes areconfigured to be saturated with scrubbing fluid. The method thencontinues to operation 804 in which top and bottom brushes are squeezed.Proceeding to operation 806, top and bottom brushes are respectivelymoved away from top and bottom surfaces of the wafer while top andbottom brushes are rotating. Next, in operation 808, top and bottomwafer surfaces are rinsed using the rinse fluid that is supplied throughrinse nozzles.

With reference to the method operation of FIG. 8B, operation 802 canfurther be understood. Starting in operation 802 a, scrubbing fluid issupplied to top and bottom brushes so as to saturate top and bottombrushes. Then, in operation 802 b, top and bottom brushes are broughtinto contact with wafer top and bottom surfaces, respectively. Next, inoperation 802 c, top and bottom surfaces of the wafer are scrubbed usingtop and bottom brushes.

Operation 804 can further be understood with reference to methodoperation depicted in FIG. 8C, in accordance with one embodiment of thepresent invention. In operation 804 a, supplying of the scrubbing fluidto top and bottom brushes is stopped. Proceeding to operation 804 b, topand bottom brushes are applied to top and bottom wafer surfaces,respectively. The scrubbing fluid is pressed out of top and bottombrushes preventing excess scrubbing fluid from dripping onto wafer topand bottom surfaces. In this manner, top and bottom surfaces of thewafer may not be re-contaminated. Beneficially, the amount of scrubbingfluid implemented is minimized while top and bottom brushes aremaintained saturated with scrubbing fluid substantially at all times.

With reference to method operation depicted in FIG. 8D, operation 808can further be understood. In operation 808 a, top and bottom rinsenozzles are provided. Then, in operation 808 b, rinse fluid is appliedonto wafer top and bottom surfaces. Rinse fluid is applied such thatrinse fluid main stream is directed to respective centers of top andbottom surfaces of the wafer. In this manner, beneficially, theconcentration of scrubbing fluid in top and bottom brushes is remainedsubstantially constant due to rinse fluid being prevented from dilutingthe concentration of the scrubbing fluid. Furthermore, in this manner,the rinse operation can be performed without having to first rinse outthe brushes.

Reference is made to flowchart 900 depicted in FIG. 9 illustratingmethod operations performed in another exemplary scrubber-rinse module,in accordance with one embodiment of the present invention. The methodbegins in operation 902 in which top and bottom wafer surfaces arescrubbed using top and bottom brushes, respectively. The brushes aresaturated with scrubbing fluid. Then, in operation 904, the brushes aresqueezed. In one example, the brushes are squeezed by applying thebrushes onto top and bottom surfaces of the wafer. In operation 906 thetop brush is moved away from the wafer top surface while the top brushis rotating. The bottom brush is also moved away from the wafer bottomsurface. Then, top and bottom wafer surfaces are rinsed using rinsefluid supplied through rinse nozzles.

FIG. 10 depicts a flowchart diagram 1000 illustrating method operationperformed by yet another scrubber-rinse module, in accordance withanother embodiment of the present invention. The method begins inoperation 1002 in which top and bottom wafer surfaces are scrubbed usingtop and bottom brushes. Top and bottom brushes are saturated withscrubbing fluid. Next, in operation 1004, top and bottom brushes aresqueezed followed by operation 1006 in which the top brush is shifted tothe side of the wafer top surface while the bottom brush is moved awayfrom the wafer bottom surface. Continuing to operation 1008, top andbottom wafer surfaces are rinsed using rinse fluid supplied throughrinse nozzles.

In one exemplary embodiment, the brush scrubber-rinse module of thepresent invention can be implemented in a clustered wafer cleaningapparatus that may be controlled in an automated way by a cleaningcontrol station. For instance, the clustered cleaning apparatus mayinclude a sender station, a scrubber-rinse module, a spin-rinse and dry(SRD) station, and a receiver station. Broadly stated, wafers initiallyplaced in the sender station are delivered, one-at-a-time, to thecleaning station. After being scrubbed and rinsed in the scrubber-rinsemodule, the wafers are dried in the SRD module. The wafers are thendelivered to the receiver station for being stored temporarily. One ofordinary skill in the art must appreciate that in one embodiment, theclustered cleaning apparatus can be implemented to carry out a pluralityof different substrate preparation operations (e.g., cleaning, etching,buffing, etc.).

Although the foregoing invention has been described in some detail forpurposes of clarity of understanding, it will be apparent that certainchanges and modifications may be practiced within the scope of theappended claims. For example, although the following parameters areassociated with an exemplary “300 mm wafer,” the parameters may bemodified for application to substrates of varying sizes and shapes suchas those employed in the manufacture of semiconductor devices and flatpanel displays, hard drive discs, flat panel displays, and the like.Additionally, the present embodiments are to be considered asillustrative and not restrictive, and the invention is not to be limitedto the details given herein, but may be modified within the scope andequivalents of the appended claims.

What is claimed is:
 1. A method for cleaning top and bottom surfaces ofa semiconductor substrate, comprising: scrubbing a top surface of thesemiconductor wafer with a top brush and a bottom surface of thesemiconductor substrate with a bottom brush, the top brush and thebottom brush being saturated and supplied with a scrubbing fluid;squeezing the top brush and the bottom brush so as to press out excessscrubbing fluid by continuing to apply the top brush against the topsurface and the bottom brush against the bottom surface of thesemiconductor substrate, but without supplying the scrubbing fluid;moving the top brush away from the top surface of the semiconductorsubstrate and the bottom brush from the bottom surface of thesemiconductor substrate; rotating the top brush to prevent dripping ontothe top surface of the semiconductor substrate; and rinsing the top andbottom surfaces of the semiconductor substrate using a rinse fluid whilecontinuing to rotate the top brush, which was squeezed to press out theexcess scrubbing fluid.
 2. A method as recited in claim 1, wherein theoperation of scrubbing the top surface and bottom surface of thesemiconductor substrate includes, supplying the scrubbing fluid to thetop brush and the bottom brush; bringing the top brush into contact withthe top surface of the semiconductor substrate and the bottom brush withthe bottom surface of the semiconductor substrate; and applying the topbrush against the top surface of the semiconductor substrate and thebottom brush against the bottom surface of the semiconductor substratewhile rotating the top brush in a first rotation direction and thebottom brush in a second rotation direction.
 3. A method as recited inclaim 1, wherein the operation of squeezing the top brush and the bottombrush includes, stopping the supplying of scrubbing fluid to the topbrush and the bottom brush; and applying the top brush against the topsurface of the semiconductor substrate and the bottom brush against thebottom surface of the semiconductor substrate while rotating the topbrush in a first rotation direction and the bottom brush in the secondrotation direction, the applying configured to press out excessscrubbing fluid from the top brush and the bottom brush.
 4. A method asrecited in claim 1, wherein the operation of rinsing the top and bottomsurfaces of the semiconductor substrate includes, supplying rinse fluidto a top rinse nozzle and a bottom rinse nozzle; and applying rinsefluid onto a center of the top surface of the semiconductor substrateand a center of the bottom surface of the semiconductor substrate.
 5. Amethod as recited in claim 4, wherein the top surface and bottom surfaceof the semiconductor wafer are rinsed such that a main stream of therinse fluid is directed onto respective centers of the top and bottomsurfaces of the semiconductor substrate.
 6. A method as recited in claim1, wherein the top brush is moved away from the top surface of thesemiconductor substrate for a top distance and the bottom brush is movedaway from the bottom surface of the substrate for a bottom distance. 7.A method as recited in claim 1 wherein the top distance and the bottomdistance are defined such that a main stream of the rinse fluid isapplied onto respective centers of the top and bottom surfaces of thesemiconductor substrate without substantially contacting the top brushand the bottom brush.
 8. A method as recited in claim 1, the methodfurther comprising: rotating the bottom brush to prevent dripping ontothe bottom surface of the semiconductor substrate.
 9. A method forcleaning a semiconductor substrate, comprising: scrubbing a top surfaceof the semiconductor substrate with a top brush and a bottom surface ofthe semiconductor substrate with a bottom brush, the top brush and thebottom brush being saturated with a scrubbing fluid; squeezing the topbrush and the bottom brush so as to press out excess scrubbing fluid;moving the top brush away from the top surface of the semiconductorsubstrate and the bottom brush from the bottom surface of thesemiconductor substrate while rotating the top brush; and rinsing topand bottom surfaces of the semiconductor substrate using a rinse fluid.10. A method as recited in claim 9, wherein the operation of scrubbingthe top surface and bottom surface of the semiconductor substrateincludes, supplying the scrubbing fluid to the top brush and the bottombrush; bringing the top brush into contact with the top surface of thesemiconductor substrate and the bottom brush with the bottom surface ofthe semiconductor substrate; and applying the top brush against the topsurface of the semiconductor substrate and the bottom brush against thebottom surface of the semiconductor substrate while rotating the topbrush in a first rotation direction and the bottom brush in the secondrotation direction.
 11. A method as recited in claim 10, wherein theoperation of squeezing the top brush and the bottom brush includes,stopping the supplying of scrubbing fluid to the top brush and thebottom brush; and applying the top brush against the top surface of thesemiconductor substrate and the bottom brush against the bottom surfaceof the substrate while rotating the top brush in a first rotationdirection and the bottom brush in the second rotation direction, theapplying configured to press out excess scrubbing fluid from the topbrush and the bottom brush.
 12. A method as recited in claim 9, whereinthe top brush and the bottom brush are configured to be compressed up toapproximately about 30 (thirty) percent of a thickness of the top brushand a thickness of the bottom brush.
 13. A method for cleaning top andbottom surfaces of a semiconductor substrate, comprising: scrubbing atop surface of the semiconductor substrate with a top brush and a bottomsurface of the semiconductor substrate with a bottom brush, the topbrush and the bottom brush being saturated and supplied with a scrubbingfluid; squeezing the top brush and the bottom brush so as to press outexcess scrubbing fluid by continuing to apply the top brush against thetop surface and the bottom brush against the bottom surface of thesemiconductor substrate, but without supplying the scrubbing fluid;moving the top brush to a side of the top surface of the semiconductorsubstrate and moving the bottom brush away from the bottom surface ofthe semiconductor substrate to prevent dripping onto the top surface ofthe semiconductor substrate; and rinsing the top and bottom surfaces ofthe semiconductor substrate using a rinse fluid.
 14. A method as recitedin claim 13, wherein the operation of scrubbing the top surface andbottom surface of the semiconductor substrate includes, supplying thescrubbing fluid to the top brush and the bottom brush; bringing the topbrush into contact with the top surface of the semiconductor substrateand the bottom brush with the bottom surface of the semiconductorsubstrate; and applying the top brush against the top surface of thesemiconductor substrate and the bottom brush against the bottom surfaceof the semiconductor substrate while rotating the top brush in a firstrotation direction and the bottom brush in the second rotationdirection.
 15. A method as recited in claim 14, wherein the operation ofsqueezing the top brush and the bottom brush includes, stopping thesupplying of scrubbing fluid to the top brush and the bottom brush; andapplying the top brush against the top surface of the semiconductorsubstrate and the bottom brush against the bottom surface of thesubstrate while rotating the top brush in a first rotation direction andthe bottom brush in the second rotation direction, the applyingconfigured to press out excess scrubbing fluid from the top brush andthe bottom brush.
 16. A method as recited in claim 13, wherein theoperation of rinsing the top and bottom surfaces of the semiconductorsubstrate includes, supplying the rinse fluid to a top rinse nozzle anda bottom rinse nozzle; and applying rinse fluid onto a center of the topsurface of the semiconductor substrate and a center of the bottomsurface of the semiconductor substrate.
 17. A method as recited in claim16, wherein the top surface and bottom surface of the semiconductorwafer are rinsed such that a main stream of the rinse fluid is directedonto the respective centers of the top and bottom surfaces of thesemiconductor substrate.
 18. A method for cleaning top and bottomsurfaces of a semiconductor substrate, comprising: scrubbing a topsurface of the semiconductor wafer with a top brush and a bottom surfaceof the semiconductor substrate with a bottom brush, the top brush andthe bottom brush being saturated with a scrubbing fluid; squeezing thetop brush and the bottom brush so as to press out excess scrubbingfluid; moving the top brush away from the top surface of thesemiconductor substrate and the bottom brush from the bottom surface ofthe semiconductor substrate while rotating the top brush; and rinsingthe top and bottom surfaces of the semiconductor substrate using a rinsefluid.
 19. A method as recited in claim 18, the method furthercomprising: rotating the bottom brush to prevent dripping onto thebottom surface of the semiconductor substrate.
 20. A method as recitedin claim 18, wherein the top brush and the bottom brush are configuredto be compressed up to approximately about 30 (thirty) percent of athickness of the brush and a thickness of the bottom brush.